On page 1157 Fiehn et al. describe a new tool for globally assessing the metabolic makeup of plants—a high-throughput technique that will complement genomic and proteomic initiatives. In the report they used gas chromatography/mass spectrometry (GC/MS) to follow the relative concentration of hundreds of metabolites in extracts from various Arabidopsis thaliana genotypes to better understand the effects of genetic variations on metabolism. The results allowed a meaningful comparative analysis of the genotypes. Data mining tools, such as principal component analysis, enabled them to assign metabolic phenotypes using the datasets (see also p. 1142).